Mule deer (Odocoileus hemionus) selectively consumed cactus fruit, browse leaves and fruit, and forbs, when present, on semidesert grass-shrub habitats in southern Arizona. Plant species utilized were generally those that have invaded and proliferated on semidesert grasslands during the twentieth century. The seasonal diet seemed deficient in phosphorus, which may affect deer reproduction and general well being.

Overwinter utilization of bitterbrush by big game can be estimated from measurement of the basal diameter and remaining length of a random sample of 100 twigs collected at the end of the browsing season. In this method, regression equations are used to predict unbrowsed twig length or weight. The range manager is thus able to obtain estimates of big game use at less expense, or to survey more area for the same cost than with more time-consuming methods.

Early growth of Sherman big bluegrass was compared with that of Nordan crested wheatgrass in central Oregon. Growth curves of the two grasses were similar between April 5 and May 15, as measured by increase in oven-dry production. Both species produced similarly during the 6-year study, except that, in 1969 big bluegrass yields were higher on May 15.

Russian wildrye was tested in the greenhouse for both interspecific and intraspecific competition using various densities of Russian wildrye, alone and in combination with cheatgrass, peppergrass, Russian thistle, and halogeton. With Russian wildrye alone, production and vigor first increased as plant density increased, then decreased at the highest density tested. Under interspecific competition, both survival and production were reduced at all weed densities tested. Combinations of species were more adverse to vigor and production of Russian wildrye than were single species of weeds.

Three collections of cane bluestem (Bothriochloa barbinodis Herter) were evaluated under three water and three harvest regimes. Dry matter yields, under natural rainfall and irrigation, averaged 3.8 and 8.7 metric tons/ha, respectively. Productivity of the three collections ranked G-866 > G-820 > PMT-333 under natural rainfall, but with irrigation, the ranking was G-820 > G-866 > PMT-333. One and two harvests per season resulted in near-equal yields, but three harvests decreased yields. Cane-bluestem forage contained about 10% protein and 0.22% phosphorus (P) in mid-June. In November, previously unclipped forage contained 4.4% protein and 0.12% P, while that clipped twice contained 7.3% protein and 0.18% P. Yield and quality of cane bluestem compared favorably with that of switchgrass (Panicum virgatum L.) grown in a similar study. Maximum production was obtained with about 77 cm of water use (rainfall + irrigation + soil water).

Yields and chemical composition of coastal Bermudagrass (Cynodon dactylon (L.) Pers.) and Rhodesgrass (Chloris gayana Kunth) grown on saline and nonsaline soils were investigated in the nonirrigated region of the Rio Grande Valley of south Texas. Forage production (3-years average) was 12.9 and 13.8 metric tons per hectare (MT/ha) for coastal Bermudagrass and 16.3 and 13.5 MT/ha for Rhodesgrass in nonsaline and saline soils, respectively, as compared with 7.7 and 7.2 MT/ha for voluntary grasses and forbs. The higher yields of coastal Bermudagrass in saline vs nonsaline soils indicates its greater salt tolerance. Soil salinity did not affect the chemical composition or crude protein content of either grass. Chemical composition of grasses varied yearly, but changes between saline and nonsaline soil treatments followed the same general trend. Growing grasses on saline soils established a mulch on the soil surface and reduced evaporation, but this was not a successful soil reclamation practice, because moisture extraction by roots from saline soil profile caused salt accumulation in the root zone.

A comparative study was made of the soils of a virgin grassland and an adjacent grazed area in Canyonlands National Park. Soils from the virgin site were finer textured than those of the grazed area, and the surface 5 cm contains a significantly lower amount of calcium. In addition, the surface 5 cm of the virgin site contains significantly greater amounts of phosphorus, potassium, and organic matter. Subsurface soils in the two parks are less dissimilar. Cryptogams on the virgin grassland appear to have an important influence on chemical characteristics of the surface 5 cm of soil. The difference in surface soils between the parks may be related to the presence of these species. Data point strongly to light winter grazing as a disturbing influence that has contributed to the differences in the surface soil and in vegetational characteristics between the sites.

Roots of plants express phenology significant to competitive relationships, as do aerial parts. The following developmental stages of root phenology are proposed: (1) germination, (2) initial root growth, (3) rapid extension of root-soil contact, (4) dormancy, and (5) death. Examples of root phenological development in seedlings of three grass species are given to demonstrate effects on competition.

The study of the relationships between annual rainfall and range production in the Mediterranean Basin and the Sahelian Sudanian tropical zones of Africa shows a close correlation between average range production and average rainfall over large geographic areas. For a given amount of rain, net production is higher in the Mediterranean than in the Sahel. The regressions developed show that, on the average, each millimeter of rainfall produces 2 kg/ha of consumable dry matter, or 0.66 Scandinavian Feed Units (FU), in the Mediterranean, whereas in the Sahelian and Sudanian zones these figures drop to 1 kg/ha and 0.40 FU.

Western wheatgrass (Agropyron smithii), blue grama (Bouteloua gracilis), and fourwing saltbush (Atriplex canescens) were subjected to multiple defoliations at moderate and heavy intensities during a 2-year period. Most heavy defoliation treatments drastically reduced herbage yield, vigor, and total nonstructural carbohydrates (TNC) of western wheatgrass. Multiple defoliations were detrimental to vigor and herbage yield of blue grama; however, defoliation treatments did not detrimentally affect root TNC levels. All defoliation treatments severely reduced the number of seedstalks, live crown cover, and TNC of fourwing saltbush, but seedstalk length and live crown diameter were less affected by the defoliation treatments. Both fringed sagewort (Artemisia frigida) and antelope bitterbrush (Purshia tridentata) subjected to two moderate defoliations during quiescence and rapid growth (or flowers developing) remained in fair to good vigor at the end of the growing season. However, both species were detrimentally affected if utilized during the later part of the growing season. Defoliation effects were generally more severe when plants were defoliated at a heavy intensity than when defoliated at a moderate intensity during the same phenological stages. Five- and six-pasture rest-rotation grazing systems were proposed to ensure that grazed plants would receive rest following critical late summer foliage utilization.